Polymer composition with improved flame retardant performance and flexibility

Abstract

A polymer composition comprising (A) a first heterophasic propylene copolymer, (B) a second heterophasic propylene copolymer, (C) a flame retardant composition and (D) an aromatic phosphate ester. The present invention also relates to a process for the preparation of the said polymer composition and use of the said polymer composition. The polymer composition has improved flame retardant performance and flexibility

1 . A polymer composition comprising
 (A) a first heterophasic propylene copolymer, wherein the MFI of the first heterophasic propylene copolymer is in the range from 3.6 to 14 g/10 min as measured according to ISO1133: 1-2011 at 230° C., 2.16 kg, wherein the first heterophasic propylene copolymer comprises a first propylene-based matrix and a first ethylene-propylene copolymer, wherein the amount of the first ethylene-propylene copolymer is in the range from 18 to 26 wt % based on the total amount of the first heterophasic propylene copolymer;   (B) a second heterophasic propylene copolymer, wherein the MFI of the second heterophasic propylene copolymer is in the range from 18 to 51 g/10 min as measured according to ISO1133: 1-2011 at 230° C., 2.16 kg, wherein the second heterophasic propylene copolymer comprises a second propylene-based matrix and a second ethylene-propylene copolymer, wherein the amount of the second ethylene-propylene copolymer is in the range from 15 to 23 wt % based on the total amount of the second heterophasic propylene copolymer;   (C) a flame retardant composition comprising at least one phosphate; and   (D) an aromatic phosphate ester,   wherein the amount of the first heterophasic propylene copolymer is in the range from 10 to 38 wt %, the amount of the second heterophasic propylene copolymer is in the range from 35 to 60 wt %, the amount of the flame retardant composition is in the range from 13 to 33 wt %, the amount of the aromatic phosphate ester is in the range from 0.3 to 13 wt % based on the total amount of the polymer composition.   
     
     
         2 . The polymer composition according to  claim 1 , wherein the aromatic phosphate ester is selected from the group consisting of resorcinol bis(diphenyl phosphate);
 tetraphenyl resorcinol bis(diphenylphosphate);   bisphenol A bis(diphenyl phosphate);   bisphenol A diphosphate;   resorcinol bis(di-2,6-xylyl phosphate),   phosphoric acid, mixed esters with [1,1′-biphenyl]-4-4′-diol and phenol; phosphorictrichloride, polymer with1,3-benzenediol,phenylester;   1,3-phenylene-tetrakis(2,6-dimethylphenyl)diphosphate;   isopropenylphenyl diphenyl phosphate;   4-phenylphenolformaldehyde phenylphosphonate;   tris(2,6-xylyl)phosphate;   resorcinol bis(di-2,6-xylyl phosphate);   bisphenol S bis(diphenyl phosphate);   resorcinol-bisphenol A phenyl phosphates.   
     
     
         3 . The polymer composition according to  claim 1 , wherein the MFI of the first heterophasic propylene copolymer is in the range from 5.1 to 12 g/10 min, as measured according to ISO1133: 1-2011 at 230° C., 2.16 kg. 
     
     
         4 . The polymer composition according to  claim 1 , wherein the MFI of the second heterophasic propylene copolymer is in the range from 22 to 42 g/10 min, as measured according to ISO1133: 1-2011 at 230° C., 2.16 kg. 
     
     
         5 . The polymer composition according to  claim 1 , wherein the density of the polymer composition is in the range from 0.956 to 1.200 g/cm3, as measured according to ISO 1183-1: 2004. 
     
     
         6 . The polymer composition according to  claim 1 , wherein the flame retardant composition comprises piperazine pyrophosphate, melamine phosphate and zinc oxide. 
     
     
         7 . The polymer composition according  claim 6 , wherein the amount of piperazine pyrophosphate is in the range from 40 to 69 wt %; the amount of melamine phosphate is in the range from 29 to 49 wt % and the amount of zinc oxide is in the range from 1 to 10 wt % based on the total amount of the flame retardant composition. 
     
     
         8 . The polymer composition according to  claim 1 , wherein the amount of the first heterophasic propylene copolymer is in the range from 15 to 30 wt %, based on the total amount of the polymer composition. 
     
     
         9 . The polymer composition according to  claim 1 , wherein the amount of the second heterophasic propylene copolymer is in the range from 40 to 55 wt %, based on the total amount of the polymer composition. 
     
     
         10 . The polymer composition according to  claim 1 , wherein the amount of the flame retardant composition is in the range from 18 to 27 wt %, based on the total amount of the polymer composition. 
     
     
         11 . The polymer composition according to  claim 1 , wherein the amount of the aromatic phosphate ester is in the range from 1.8 to 8.0 wt %, based on the total amount of the polymer composition. 
     
     
         12 . The polymer composition according to  claim 1 , wherein the polymer composition has a UL94 rating of V0 at 0.8 mm, wherein the specimens are conditioned in an environment of 23° C., 50% RH for 48 hours after forming and prior to UL94 measurement. 
     
     
         13 . The polymer composition according to  claim 1 , wherein the polymer composition has a tensile elongation at break of at least 42% as measured according to ISO527-1: 2019 using 1A specimen. 
     
     
         14 . Process for the preparation of the polymer composition according to  claim 1  comprising the sequential steps:
 providing the first heterophasic propylene copolymer, the second heterophasic propylene copolymer, the flame retardant composition and the aromatic phosphate ester; and 
 mixing the first heterophasic propylene copolymer, the second heterophasic propylene copolymer, the flame retardant composition and the aromatic phosphate ester in an extruder. 
 
     
     
         15 . An article comprising the polymer composition according to  claim 1 .